Tyre advice

[Fromow]

Hi all
So I’m currently running 275/40/20 tyres on 9.5J et35 wheels. I recently installed B14s to my 4motion, the rears are Fine but I can’t get the front down to the height I want because the wheels rub on the arch mainly In the screw area that holds the inner arch to the outer.
My question being a 4 motion can I slim down the front tyres to a 265 or 255 /40 and keep the circumference the same all round. Not sure if doing it will affect the 4wd.
Any advice greatly welcomed

 

[dubber36]

The circumference won't remain the same if you alter the width. The '40' is the aspect ratio, so 40% of the tyres width.

 

[DaveD]

I'm with dubber36, front and rear tyres must be identical sizes on 4motion to avoid expensive repairs to the transmission.

 

[Fromow]

@dubber36 Thanks for that.
So working out the percentage ratio to get an identical circumference I will need a 245/45/20!!!! not sure this will stretch or look ok on a 9.5j wheel

 

[The Van Cave]

Hi all
So I’m currently running 275/40/20 tyres on 9.5J et35 wheels. I recently installed B14s to my 4motion, the rears are Fine but I can’t get the front down to the height I want because the wheels rub on the arch mainly In the screw area that holds the inner arch to the outer.
My question being a 4 motion can I slim down the front tyres to a 265 or 255 /40 and keep the circumference the same all round. Not sure if doing it will affect the 4wd.
Any advice greatly welcomed

As the others have said, you'll need to replace all 4 tyres for a 265/40 or 255/40 to keep the circumference the same. Also, are you T32? If so you'll need to check load ratings. You could try a 245/45 on the front, they will be OK, but yes, they'll be a stretch on 9.5" rims.

One other option to try, before you change your tyres: You can remove that screw, push the arch liner up behind the retaining tab and push the tab back on itself a bit. Leave the screw out and that can cure the rub in that area.

 

[dubber36]

This might help with your calculations https://www.willtheyfit.com/

When you stretch a tyre over a narrower rim, the side walls will be at more of an angle, so the actual profile height will be reduced. That's another factor to be considered when comparing one tyre size with another. The attached calculator will take this into account.

 

[Fromow]

@ChrisR it’s a T30, I’ve already removed the screw but not moved the shield and bent the tab back I’ll do that next I think.
@dubber36 that’s a great calculator thank you!! comparing the 275 and stretched 245 there’s only 1.5 mm difference in circumference. Just gutted I’ve got plenty of tread left on the 275s

 

[The Van Cave]

@ChrisR it’s a T30, I’ve already removed the screw but not moved the shield and bent the tab back I’ll do that next I think.
@dubber36 that’s a great calculator thank you!! comparing the 275 and stretched 245 there’s only 1.5 mm difference in circumference. Just gutted I’ve got plenty of tread left on the 275s

Let us know how you get on after moving the liner and tab.

Just a couple of other points to consider if you change all 4 tyres:
For a T30 you need minimum load rating of 102 which I don't think you can get in a 255/40. A 265/40 all around might work, I run them and I'm quite low, albeit my wheels are different widths and offsets to yours so don't come out quite as far. What might work if you change all 4 is a 275/35, that'll give you a 14mm lower profile than 275/40 and might help cure the rubbing.

If you decide to change the fronts to 245/45 then I have a pair of Falken FK510 in that size with 7mm tread left that we could do a deal on, PM me if that's the route you decide to take, they are a lovely tyre.